Advances in large scale integration are producing integrated circuits with ever diminishing geometries and increasing densities. Associated with the increase in density is an increase in the amount of heat generated by a semiconductor die per square unit of area. The need to effectively dissipate this heat has led to the incorporation of metal heat spreaders in packaged semiconductor devices. Metal heat spreaders typically contact the semiconductor die or a die pad on which the semiconductor die is mounted and serve as a path of low thermal impedance to efficiently conduct the heat generated by the die to the exterior of the packaged device.
In semiconductor devices having an injection-molded plastic package, the metal heat spreader may be either entirely encapsulated or may be only partially encapsulated so that a surface of the heat spreader is exposed. A mechanical lock is often used in molded plastic packaged devices to help secure the metal heat spreader to the plastic mold compound.